Living nearby and traveling under the overpass twice a day, (NB and SB), the striking thing to me was despite the inspections that identified potential locations that should be noted, the lone 30 MPH curve upon an overpass approach was largely ignored.
I don't really believe the lack of PTC was the issue, though it clearly has benefits, as much as the Engineers lack of experience on the line, particularly at the time of day the accident occurred.
Sad.